[ The head shake just keeps whirring along. Shouldn't she be getting dizzy by now? ]

You've already met your manful courtesy quota for the day just by listening to me complain so much! And it's the old-timers who have to look after the newcomers, so it's only natural that I treat! And moreover! How old are you?

[ Granted, the difference can't be very big either way, but just from looking at Zenitsu she's pretty sure he isn't older than her, at least. ]